Simmons II Flashcards
Where does THF come from?
B9
What does THF do?
Important cofactor in biosynthesis of purines and thymidylate
Form of THF in purine synthesis?
N10
Form of THF in pyrimidine synthesis?
N5N10
What is Megaloblastic anemia?
- Result of folate deficiency in which blast cells are unable to replicate DNA and divide
- They just keep on getting bigger leading to weak membrane and poor O capacity
What are blast cells?
Premature RBC with no nucleus
What does 5-methyl-THF do?
- Converts homocysteine to methionine
- Homocysteine is toxic and methionine is used in AA metabolism
- This is the only reaction 5-methyl-THF is used in and the reaction converts it back to THF
- B12 required for reaction
What reaction requires B12?
homocysteine to methionine necessary for AA metabolism
What deficiency does b12 deficiency cause?
Folate
What are the purine bases?
Adenine
Guanine
2 ring structure
Nucleotide/side difference?
Nucleotide is side with added phosphate
Three pyrimidines
Cytosine, uracil, and thiamin
What does purine synthesis start with?
5 ribose phosphate
Branchpoint in purine synthesis?
IMP - can become amp or gmp
What is required for purine synthesis?
THF, AAs, Co2
What drug inhibits purine synthesis?
6 mercaptopurine
What cancer is 6 mercaptopurine used for?
ALL
Why do tumor drugs cause increased risk of infection?
WBCs formation is inhibited in marrow as well making susceptible to infection
What is necessary for pyrimidine synthesis?
Co2, glutamine, and aspartate are necessary for synthesis
What drug is useful in treating reumatoid arthritis?
Leflunomide inhibitis pyrimidine synthesis stopping WBC inflamatory reaction
What does Thymidylate synthase do?
- converts dUMP to dTMP
Why is Thymidylate synthase good target for cancer drug?
Thymine is only in DNA and not RNA
What does 5 fluorouracil do?
Blocks action of thymidylate synthase
What is Dihydrofolate?
Product of pyrimidine synthesis that is toxic and needs to be converted by to tetrahydrofolate
